塔里木板块东南缘大敖包沟铜镍矿床岩石地球化学特征及其地质意义  

Geochemical characteristics of the Daaobaogou Cu-Ni sulfide deposit in the southeastern margin of the Tarim Plate and their geological implications

作　　者：冯永忠[1] 康鸿杰[1] 周超[1] 王振华[1] 于飞[1] 于漫[1] 孔立[1] 牛刚[1] 王东阳[1] 

机构地区：[1]甘肃省国土资源规划研究院,兰州730000

出　　处：《兰州大学学报（自然科学版）》2015年第4期496-502,507,共8页Journal of Lanzhou University(Natural Sciences)

基　　金：2013年度"陇原青年创新人才扶持计划"项目(2200199)

摘　　要：大敖包沟铜镍矿位于塔里木板块东南缘,其发现是近年来该区带找矿的重大突破.已发现岩体具有全岩矿化特征,初步划分3个岩相,由橄榄辉石岩、辉石岩和辉长岩组成,岩石w(Si O2)集中于44.2%～49.1%,具低铝、低钛、低碱、高镁、高铁特征,m/f=1.73～6.10,平均4.05,属于铁质超镁铁质岩.在微量元素原始地幔标准化蛛网图上,岩石具有相对富集大离子亲石元素Rb、Ba、K、Sr、LREE、U、Pb,相对亏损高场强元素Nb、Ta、Zr、Hf,以及较高的w(Zr)/w(Y)(0.83～6.41)、w(Ta)/w(Yb)(0.14～0.19)和较低的w(Zr)/w(Nb)(2.65～31.92)地球化学特征.岩石ΣREE=28.25×10-6～45.87×10-6、(w(La)/w(Yb))N=2.56～10.06、δ(Eu)=0.76～1.06,具有LREE相对富集特征.综合大敖包沟岩体地质特征和区域地质背景,推断大敖包沟岩体可能形成于塔里木板块东南缘一个大陆裂谷环境.The Daaobaogou Cu-Ni deposit located at the southeastern margin of the Tarim Plate is an important exploring site in this area in recent years. The intrusion is characterized by whole-rock mineralization and can be divided into three rock facies： olivine pyroxenolite, pyroxenite, gabbro. The w（SiO2） of the intrusions ranges from 44.2% to 49.1%, having have low A1, Ti, total alkalis content, high Mg, TFe, m/f =1.73-6.10, with an average of 4.05 and thus falling into the range of ferrous-ultramafic rocks. On the PM-normalized trace element spider diagram, they are enriched in LILE （Rb, Ba, K, Sr）, LREE, U, Pb, depleted in HSFE（Nb, Ta, Zr, Hf）, and with relatively high w（Zr）/w（Y）（0.83-6.41）, w（Ta）/w（Yb）（0.14-0.19） and low w（Zr）/w（Nb） （2.65-31.92）. They are slightly enriched in LREE with （w（La）/w（Yb））N ranging from 2.56 to 10.06. EREE contents are 28.25×10^-6～45.87×10^-6 and 5（Eu） are 0.76-1.06. Combined with analyses of geological and tectonic characters of the Daaobaogou intrusion, we concluded that the Daaobaogou intrusion was formed in a continental rift environment at the southeastern margin of the Tarim Plate.

关 键 词：铜镍矿床 超镁铁质岩 地球化学 大陆裂谷 大敖包沟 

分 类 号：P597.3[天文地球—地球化学] P588.125[天文地球—地质学]